The announcement on Monday that Fox News was parting ways with its top-rated prime-time host, Tucker Carlson, stunned people in Donald J. Trump’s orbit. The former president himself was surprised by the news, according to a person with direct knowledge, and his eldest son, Donald Trump Jr., who is a close friend of Mr. Carlson’s, described the network’s decision as “mind-blowing.”
“I think it changes things permanently,” Donald…